The flue gases originating from coal or oil fired combustion systems contain particulate matter, in the form of "fly ash", as well as oxidation products such as sulphur dioxide, in such quantity as to make their discharge directly into the ambient atmosphere unacceptable.
It is known that flue gases can be cleaned by contact with a scrubbing liquid which comprises a slurry of calcium carbonate in water, as taught in U.S. Pat. No. 3,795,486 to Frank A. Ekman. In order to accomplish the desired degree of cleansing in intervals of acceptably short length, and using apparatus of practical size, it is necessary that the contact between the gas and the liquid be of great intimacy, and to accomplish this it has been suggested to provide arrays of elongated, parallel, spaced rod-like elements extending across a flow chamber, downstream of the admission site for slurry, to substantially restrict the cross sectional area of the gas flow and to enturbulate the flow by introducing eddys and cross currents. The elements quickly become wet with the treating slurry, to increase the area of liquid-to-gas contact, and the eddys and cross currents cause sharp changes in the direction of gas flow to inertially precipitate particulate matter upon the wet surfaces, from which it is carried away with the liquid as it drips off.